The overall objective of this research proposal is the determination of characteristics of infants, children and young people that predict or lead to, the development of essential hypertension in adulthood. A cohort with extensive follow-up data already recorded will be studied. From data collected from birth through the seventh year from over 8,000 children (the Boston cohort of a collaborative peri-natal study), the determinants of the seventh year blood pressure will be sought from pre-natal items (genetic-familial, gestational), peri-natal items, and post-natal characteristics and environment (infant feeding, growth patterns, salt intake, personality and behavioral characteristics, socioeconomic state of family, etc.). Subsets of this cohort, who will be 14 to 18 years old in 1977, will be recalled for repeat examinations. Measurements of blood pressure, body size and obesity, cardiac output (by echocardiography), and behavioral characteristics will be performed to relate interim physical, social and psychological parameters to the course of blood pressure. Similar measurements in their parents will permit an evaluation of the familial aggregation of such characteristics. The longitudinal and developmental data from this cohort will bear on existing hypotheses about genetic-familial, physical, social, and behavioral factors involved in the development of hypertension. Guidelines for well-child pediatric practice, for early screening and detection, and for intervention in children detected to be risk can then be formulated.